In FY 2017, we continued our investigation of virulence factors that contribute to Staphylococcus aureus pathogenesis and immune evasion. The focus is on understanding which factors define the virulence potential of highly virulent MSSA and MRSA clones, in particular of community-associated MRSA. Much of our work is currently still focussed on phenol-soluble modulins (PSMs), toxins that we discovered in 2007. Current efforts are aimed at understanding the regulation and export of PSMs. With regard to the former, we discovered in the past year that PSMs directly interact with a regulator protein to control the genes involved in their export. This work has been published in MBio (Joo et al.).